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See Operculum.

The principal opercular bone or operculum of fishes.

Closed by a lid or cover, as the capsules of the mosses.

Having the lid removed; -- said of the capsules of mosses.

Having no operculum; -- said of certain gastropod shells.

The interopercular bone.

Situated in front of the operculum; pertaining to the preoperculum. -- n.

Situated below the operculum; pertaining to the suboperculum. -- n.

Destitute of an operculum, or cover.

the terminal chambers of ammonite shells. Some authors consider them to be jaws; others, opercula.

The postero-inferior opercular bone, in fishes.

istinguished from the aquatic snails are Pulmonifera, and belong to the Geophila; but the operculated land snails of warm countries are Dioecia, and belong to the Tænioglossa. See Geophila, and Helix. -- Land spout, a descent of cloud and water in a conical form during the occurrence of a tornado and heavy rainfall on…

Having numerous spiral coils round a center or nucleus; -- said of the opercula of certain shells.

Any one of the bony plates which support the gill covers of fishes; an opercular bone.

Any lidlike or operculiform process or part; as, the opercula of a dental follicle.

tinibranchiate mollusks, belonging to Paludina, Melantho, and allied genera. They have an operculated shell which is usually green, often with brown bands. See Illust. of Pond snail, under Pond.

rigla lyra), having a large head, with prominent nasal projection, and with large, sharp, opercular spines.

Pertaining to the Pomacentridæ, a family of bright-colored tropical fishes having spiny opercula; -- often called coral fishes.

athing snails (Pulmonifera) belonging to Limnæa, Physa, Planorbis, and allied genera. The operculated species are pectinibranchs, belonging to Melantho, Valvata, and various other genera. -- Pond spice (Bot.), an American shrub (Tetranthera geniculata) of the Laurel family, with small oval leaves, and axillary cluster…

The anterior opercular bone in fishes.